Drop back sofa bed



FIG. 1 is a front view of the drop back sofa bed in a first position;

FIG. 2 is a front, right side, perspective view of the drop back sofa bed in the first position;

FIG. 3 is a back, right side, perspective view of the drop back sofa bed in the first position;

FIG. 4 is a right side view of the drop back sofa bed in the first position; and,

FIG. 5 is a front, right side, perspective view of the drop back sofa bed in a second position. 

CLAIM The ornamental design for a drop back sofa bed, as shown and described. 